1. Field
The following description relates to a network transmission technology, and more specifically, to a base-band transmission technology.
2. Description of the Related Art
Communication service operators worldwide require more distributed base stations in order to process the exponentially increasing data traffic. The Common Public Radio Interface (CPRI) is a digital interface to be used for processing data traffic, for which defined standard specifications only support up to 10 Gbps of bandwidth and thus cannot meet the requirements for processing bandwidth of several tens of Gbps.
To address such a problem, standardization of CPRI in-phase/quadrature (IQ) data compression technologies is in progress, and plans for system application have been announced. Future mobile communication technologies will require a greater number of downsized base stations, and the need for digital interfaces will continue to increase to accommodate the increasing number of base stations. Also, it is predicted that the need for new technologies will continue to increase in the field of data compression in light of such growing demand.
KDDI, a Japanese company, and ALU, a U.S. company, have proposed compression algorithms for the Common Public Radio Interface (CPRI) specifications that specify transmission of distributed base stations. The aforesaid compression algorithms both utilize up-down sampling (generally used as decimation) to compress IQ data elements so that data that is meaningful in the frequency domain can be compressed into a narrower bandwidth. Furthermore, if nonlinear quantization processing (suggested by KDDI) and block-scaling processing (suggested by ALU) are carried out, the efficiency of data compression and recovery may be increased.
The aforesaid compression and recovery technologies can reduce an error vector magnitude loss, as well as reduce latency caused by compression and recovery within, for example, 20 sec. However, it still has limitations in terms of compression rate.